ARTIFICIAL SATELLITE OBSERVING LAB
Astronomy 1010-1020 Extro-class Lab
Name ____________________________
Class-Section _________________
Discussion: There are literally thousands of artificial satellites in various orbits about the Earth.
Under the right conditions, many of these are easily visible as bright star-like objects gliding
rapidly across the sky. In this extro-class lab students will use the Heavens-Above.com website
to predict and observe easily visible passes of the International Space Station (ISS) and “Iridium
Flares”. Iridium Flares are predictable bright sun glints off of a system of polar orbiting satellites
used for a global satellite phone network. This system of satellites is called the Iridium Satellite
Constellation.
Successful completion of this exercise will help students familiarize themselves with several
astronomical concepts including celestial coordinates (altitude and azimuth), magnitude scale,
star charts, constellations, and even orbital mechanics.
Procedure:
1.
Access heavens-above.com
2.
Follow the instructions and register or select a site as an anonymous user. If you plan to
observe from North Georgia Astronomical Observatory (NGAO) you will need to input the
following coordinates: latitude = 34.521O (north), longitude = -84.054O (west - the neg.
sign indicates west longitude). (See main page example.)
3.
Go to the satellite section and select 10 day predictions for: ISS or Iridium Flares: next 7
days.
4.
Selecting the ISS or Iridium Flare predictions will bring you to the prediction table pages.
Print out the prediction table pages and use them to select which ISS passes or Iridium
Flares to try and observe. (See ISS and Iridium Flare prediction table page examples.)
5.
i.
Use the prediction tables for the ISS and select only those ISS passes brighter
than1st magnitude (click on the mag column header for a review of astronomical
magnitude) and with maximum altitudes (click on the alt & azm column headers for
a review of alt-azm coordinates) above approximately 20 degrees. Mark the
selected passes on the table with an asterisk.
ii.
6.
Use the prediction tables for the Iridium Flares and select only those Iridium Flares
brighter than -2 magnitude. Mark the selected flares on the table with an asterisk
Go back to the Heavens-Above Main Page and click on the Astronomy: whole sky chart
section. Go to the controls at the bottom of the chart and click on “Black on white” (for
printing the sky chart) and input a date and time close to one or more of the potential ISS
passes or Iridium Flares. It might be possible to use one chart for several ISS and Iridium
Flares over the 7 to 10 day period of the predictions. Click “Submit” to display the sky
chart for the desired date and time and then print out the chart. If need be, you can print
out a different chart for each observation, but normally it should be possible to use one
sky chart for several observations. (See sky chart example.)
7.
Now you should attempt to observe the selected ISS passes and Iridium Flares. Use the
printed sky charts to record the path of the observed satellites. Record the time, date,
satellite name, and observing location beside each recorded path on the sky chart.
8.
You may repeat this procedure until you have successfully observed the number of
satellites necessary to achieve the desired grade on the lab. Scoring is as follows:
i.
ii.
iii.
iv.
9.
Five (5) points (out of 10) for the web information pages. (The marked prediction
table pages and the associated sky chart pages.)
One (1) point for each successful Iridium Flare observation, recorded on sky chart.
Two (2) points for each successful ISS observation, recorded on sky chart.
Any combination of observations may be made up to a total of ten (10) points for
the observations (15 points out of 10 for the total lab).
Final deadline: Last day of classes during the semester. Please turn in the lab as soon
as your observations are complete. You may turn in multiple sets of observations during
the semester, but the web information pages are counted only once.
Heavens-Above Main Page example:
ISS prediction table example:
Iridium Flare prediction table example:
Sky Chart example:
Note: This sky chart would be usable for all of the example prediction
table ISS passes and for at least three of the example prediction table
Iridium Flares.